Implantable sensor and integrity tests therefor

• US 6,387,048 B1
• Filed: 07/22/1999
• Issued: 05/14/2002
• Est. Priority Date: 10/20/1997
• Status: Expired due to Term

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Shah, Rajiv, Schulman, Joseph H.
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US09/360,343
• Time in Patent Office: 1,027 Days
• Field of Search: 600/300, 600/345-361, 600/365, 600/372, 600/373, 600/377-486, 600/508, 600/509, 600/510
• US Class Current: 600/300
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement

Abstract

An implantable sensor includes electronic circuitry for automatically performing on a periodic basis, e.g., every 1 to 24 hours, specified integrity tests which verify proper operation of the sensor.

Claims

1. An implantable sensor comprising:

an implantable housing;

at least one sensing device integral with said implantable housing for sensing a physiological parameter;

measurement circuitry integral with said implantable housing and coupled to said at least one sensing device for generating an electrical signal indicative of a sensed parameter; and

wherein

said measurement circuitry is configured for automatically performing on a periodic basis at least one specified integrity test which verifies proper operation of said sensing device in combination with said measurement circuitry.

2. The implantable sensor of claim 1 wherein:

at least a portion of said implantable housing is hermetically-sealed;

said measurement circuitry comprises an integrated circuit (IC) chip inside of said housing; and

said sensing device comprises at least one electrode external to said hermetically sealed portion of said housing.

3. The implantable sensor of claim 2 wherein said at least one specified integrity test comprises means for measuring voltage, current, or impedance between said at least one electrode and a specified reference point.

4. The implantable sensor of claim 3 wherein said specified reference point comprises a point external to said hermetically-sealed housing.

5. The implantable sensor of claim 3 wherein said specified reference point comprises a point internal to said hermetically-sealed housing.

6. A method of testing an implantable sensor, said sensor including measurement circuitry for sensing a physiological parameter from a sensing device and generating an output signal indicative thereof, said method comprising the steps of:

placing a sensing device integral with said sensor for sensing a physiological parameter;

placing measurement circuitry integral with said sensor that performs at least one integrity test designed to verify proper operation of said sensing device in combination with said measurement circuitry; and

periodically performing said at least one integrity test while said implantable sensor remains implanted.

7. The method of claim 6 further including implanting at least three sensors in the same general tissue area, and wherein said step of periodically performing said at least one integrity test comprises periodically monitoring said output signal from each of said at least three sensors and checking to ensure that said output signals remain within a specified tolerance of each other.

8. The method of claim 6 further including implanting at least three senors in the same general tissue area, and wherein said step of periodically performing said at least one integrity test comprises periodically monitoring a voltage, current or impedance measurement associated with each of said at least three sensors and checking to ensure that all three measurements remain within a specified tolerance of each other.